Emotet — Office (OLE) / .XLS malware analysis

Static analysis result for SHA-256 36bd9d6338b1d2cc…

MALICIOUS

Office (OLE) / .XLS

74.0 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-03-28
MD5: 236531fbe0614c238aaa3974736f8e38 SHA-1: bf2700b9996dc7b19f146f178104f7ccf71ec795 SHA-256: 36bd9d6338b1d2cc24c0fd37089a4cbc49e2e086e738007e56150e9640acda3b
302 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1218.011 System Binary Proxy Execution: Rundll32 T1059.001 PowerShell T1105 Ingress Tool Transfer

The file contains Excel 4.0 macros with an Auto_Open entry, which is a known technique for executing malicious code. The macros reconstruct a command line that uses regsvr32.exe to download and execute a payload from one of the embedded URLs. ClamAV detection further confirms its malicious nature, identifying it as an Emotet downloader variant.

Heuristics 7

  • Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAME
    oletools recovered an Auto_Open / Auto_Close entry from an Excel 4.0 macro sheet. The raw BIFF name can be tokenized or partially opaque to byte-string checks, but the recovered macro listing confirms the workbook has an XLM auto-execution entry.
  • XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and dangerous XLM formula APIs that can invoke programs, write files, or transfer control without VBA.
  • URL reconstructed from XLM cell array (6 URLs) critical OLE_XLM_CELL_ARRAY_URL
    Excel 4.0 macro sheet stages its payload URL across the BIFF8 Shared String Table (one quoted-char SST entry concatenated with & at runtime) or across individual numeric cells (one ASCII charcode per cell). The reconstructed URL is invisible to literal-bytes URL extraction because it is never contiguous in the workbook stream. URLs were recovered by walking the BIFF8 record stream and decoding SST entries plus LABELSST/RK/NUMBER cells.
  • ClamAV: Xls.Downloader.Emotet-b680c97f3ec1c03e-9951030-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-b680c97f3ec1c03e-9951030-0
  • LOLBin token sequence in document text high SE_LOLBIN_RUN_COMMAND
    Extracted document text contains a Windows script/execution tool name (PowerShell, mshta, cmd, rundll32, regsvr32, …) within 220 characters of a dangerous flag, command verb, or URL. This is a visible 'run this' instruction in HTML/PDF/RTF lure bodies, or — in macro-laden Office files — the macro's own string-pool entries appearing adjacent in extracted text.
  • Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN
    Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://www.clasite.com/blogs/bhaAB/
    • http://fmesperanza945.com/fonts/Mta/
    • https://classicpaint.net/wp-content/Vx6iP4KOyoZuiwsyW/
    • http://clipacc.com/img/doXw68d7bqxxhwuxNb0N/
    • http://clanwatson.co.uk/personal/DxlCbK5yxbqq1jqP/
    • http://clovisclark.com/cristina/oHhyKOoFQilsF2EljI/

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
09766ace40a05da85050d6e9ec7093d6722df7e33a81547c627ee8e0e9dbf1ff		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6951 bytes

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